ppm: Calculate ppm values
In RMassBank: Workflow to process tandem MS files and build MassBank records

Description Usage Arguments Details Value Author(s) Examples

Calculates ppm values for a given mass.

1	ppm(mass, dppm, l = FALSE, p = FALSE)

`mass`	The "real" mass
`dppm`	The mass deviation to calculate
`l`	Boolean: return limits? Defaults to FALSE.
`p`	Boolean: return ppm error itself? Defaults to FALSE.

This is a helper function used in RMassBank code.

By default (l=FALSE, p=FALSE) the function returns the mass plus the ppm error (for 123.00000 and 10 ppm: 123.00123, or for 123 and -10 ppm: 122.99877).

For l=TRUE, the function returns the upper and lower limit (sic!) For p=TRUE, just the difference itself is returned (0.00123 for 123/10ppm).

Michael A. Stravs, Eawag <michael.stravs@eawag.ch>